One step reconstruction of carbon/P zeolite from coal gasification slag and its adsorption mechanism for crystal violet

WU Yuhua; LIU Caizhu; MA Yulong; SUN Yonggang; JI Wenxin; ZHU Li; BAI Hongcun

doi:10.13225/j.cnki.jccs.2024.0579

Abstract：The efficient resource utilization of coal gasification slag is a key issue that urgently needs to be addressed in the fields of energy,environmental protection,and sustainable development.As the main byproduct of the coal gasifica-tion process,the annual emissions of coal gasification fine slag are enormous.However,its traditional processing methods face technical bottlenecks such as difficulty in separating carbon ash,low atomic utilization rate,and severe secondary pol-lution,which seriously restrict its resource utilization efficiency.This study innovatively developed a one-step reconstruc-tion technology for in-situ activation of coal gasification fine slag,and successfully prepared carbon/P-type zeolite com-posite materials(CPCMs),achieving efficient synergistic activation of silicon,aluminum,and carbon elements in fine slag under mild conditions.The composite material has a flower shaped multi-level pore structure with a specific surface area of 107 m2/g,mainly composed of mesopores.In addition,by regulating the alkaline leaching time and calcination condi-tions,P-type zeolite in CPCMs can be directionally converted into sodium cross zeolite.CPCMs exhibit excellent adsorp-tion performance for crystal violet dye in water,with a maximum adsorption capacity of 454.6 mg/g at 303 K.Its adsorp-tion behavior conforms to a quasi second order kinetic model,R2>0.995,Indicating that chemical adsorption is dominant.The isothermal adsorption data is highly consistent with the Langmuir model,confirming the uniform adsorption charac-teristics of the monolayer.Thermodynamic analysis shows that the adsorption process is spontaneous endothermic,ΔG<0,ΔH=33.92 kJ/mol,ΔS>0.Mechanism studies have shown that adsorption is due to multi mechanism coupling:the mesoporous confinement effect and electrostatic attraction of P-type zeolite,and the adsorption capacity is significantly in-creased when pH>7;π-π conjugation of residual carbon components;Ionic exchange and complexation between metal ions and crystalline violet cations in composite materials.It is worth noting that CPCMs maintain stable adsorption per-formance over a wide salinity range and exhibit good anti-interference ability.This study not only achieved high-value re-source utilization of coal gasification fine slag,but also provided economically efficient adsorption materials for industrial wastewater treatment,which has important environmental and economic benefits.